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Strength grading of sawn timber in Europe: an explanation for engineers and researchers

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Abstract

This paper is a concise explanation of the normative background to strength grading in Europe, addressing important aspects that are commonly misunderstood by structural engineers and timber researchers. It also highlights changes that are being made to the standards to: incorporate requirements of the construction products regulations; add improvements to the system to accommodate the latest knowledge and technology; and widen the application of the standards. Where designs need to be optimised, there is an opportunity to use the system more intelligently, in combination with the latest technology, to better fit design values to the true properties of the timber resource. This can bring a design enhancement equivalent to effort improving other aspects of the structure, such as connectors and reinforcement. Parallel to this, researchers working on other aspects of structural improvement need to understand what grades really mean in respect of the properties of the timber, in order to correctly analyse the results of testing. It is also useful to know how techniques used in grading can assist with material properties characterisation for research. The amount of destructive testing involved in establishing machine grading settings and visual grading assignments presents a barrier to greater use of local timber, and diversification of commercial species, so it is important that any researcher assessing the properties of such species should consider, from the outset, doing the research in a way that can contribute to a grading dataset at a later date. This paper provides an overview of what is required for this.

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Acknowledgments

The authors are grateful to COST Action FP1004 “Enhance mechanical properties of timber, engineered wood products and timber structures” for enabling this collaboration.

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Authors and Affiliations

  1. Centre for Wood Science and Technology, Edinburgh Napier University, 10 Colinton Road, Edinburgh, EH10 5DT, UK

    Dan Ridley-Ellis

  2. Holzforschung München, Technische Universität München, Winzererstr. 45, 80797, Munich, Germany

    Peter Stapel

  3. Institute of Structures and Transport, Universidad de la República, Julio Herrera y Reissig 565, 11300, Montevideo, Uruguay

    Vanesa Baño

Authors
  1. Dan Ridley-Ellis
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  2. Peter Stapel
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  3. Vanesa Baño
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Correspondence to Dan Ridley-Ellis.

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Ridley-Ellis, D., Stapel, P. & Baño, V. Strength grading of sawn timber in Europe: an explanation for engineers and researchers. Eur. J. Wood Prod. 74, 291–306 (2016). https://doi.org/10.1007/s00107-016-1034-1

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